#include <ctype.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define lstrlib_c
#define LUA_LIB

#include "lua.h"

#include "lauxlib.h"
#include "lualib.h"


/* macro to `unsign' a character */
#define uchar(c)        ((unsigned char)(c))


static int 
str_len (lua_State *L)
{
	size_t l;
	luaL_checklstring(L, 1, &l);
	lua_pushinteger(L, l);

	return 1;
}


static ptrdiff_t
posrelat (ptrdiff_t pos, size_t len)
{
	/* relative string position: negative means back from end */
	return (pos>=0) ? pos : (ptrdiff_t)len+pos+1;
}


static int 
str_sub (lua_State *L) 
{
	size_t l;
	const char *s = luaL_checklstring(L, 1, &l);
	ptrdiff_t start = posrelat(luaL_checkinteger(L, 2), l);
	ptrdiff_t end = posrelat(luaL_optinteger(L, 3, -1), l);
	if (start < 1) 
		start = 1;
	if (end > (ptrdiff_t)l) 
		end = (ptrdiff_t)l;
	if (start <= end)
		lua_pushlstring(L, s+start-1, end-start+1);
	else 
		lua_pushliteral(L, "");

	return 1;
}


static int 
str_reverse (lua_State *L)
{
	size_t l;
	luaL_Buffer b;
	const char *s = luaL_checklstring(L, 1, &l);
	luaL_buffinit(L, &b);
	while (l--) luaL_addchar(&b, s[l]);
	luaL_pushresult(&b);

	return 1;
}


static int 
str_lower (lua_State *L) 
{
	size_t l;
	size_t i;
	luaL_Buffer b;
	const char *s = luaL_checklstring(L, 1, &l);
	luaL_buffinit(L, &b);
	for (i=0; i<l; i++)
		luaL_addchar(&b, tolower(uchar(s[i])));
	luaL_pushresult(&b);

	return 1;
}


static int
str_upper (lua_State *L)
{
	size_t l;
	size_t i;
	luaL_Buffer b;
	const char *s = luaL_checklstring(L, 1, &l);
	luaL_buffinit(L, &b);
	for (i=0; i<l; i++)
		luaL_addchar(&b, toupper(uchar(s[i])));
	luaL_pushresult(&b);

	return 1;
}

static int 
str_rep (lua_State *L) 
{
	size_t l;
	luaL_Buffer b;
	const char *s = luaL_checklstring(L, 1, &l);
	int n = luaL_checkint(L, 2);
	luaL_buffinit(L, &b);
	while (n-- > 0)
		luaL_addlstring(&b, s, l);
	luaL_pushresult(&b);

	return 1;
}


static int
str_byte (lua_State *L)
{
	size_t l;
	const char *s = luaL_checklstring(L, 1, &l);
	ptrdiff_t posi = posrelat(luaL_optinteger(L, 2, 1), l);
	ptrdiff_t pose = posrelat(luaL_optinteger(L, 3, posi), l);
	int n, i;
	if (posi <= 0) posi = 1;
	if ((size_t)pose > l) pose = l;
	if (posi > pose) return 0;  /* empty interval; return no values */
	n = (int)(pose -  posi + 1);
	if (posi + n <= pose)  /* overflow? */
		luaL_error(L, "string slice too long");
	luaL_checkstack(L, n, "string slice too long");
	for (i=0; i<n; i++)
		lua_pushinteger(L, uchar(s[posi+i-1]));

	return n;
}


static int
str_char (lua_State *L) 
{
	int n = lua_gettop(L);  /* number of arguments */
	int i;
	luaL_Buffer b;
	luaL_buffinit(L, &b);
	for (i=1; i<=n; i++)
	{
		int c = luaL_checkint(L, i);
		luaL_argcheck(L, uchar(c) == c, i, "invalid value");
		luaL_addchar(&b, uchar(c));
	}
	luaL_pushresult(&b);

	return 1;
}


static int 
writer (lua_State *L, const void* b, size_t size, void* B) 
{
	(void)L;
	luaL_addlstring((luaL_Buffer*) B, (const char *)b, size);

	return 0;
}


static int
str_dump (lua_State *L)
{
	luaL_Buffer b;
	luaL_checktype(L, 1, LUA_TFUNCTION);
	lua_settop(L, 1);
	luaL_buffinit(L,&b);
	if (lua_dump(L, writer, &b) != 0)
		luaL_error(L, "unable to dump given function");
	luaL_pushresult(&b);

	return 1;
}



/*
** {======================================================
** PATTERN MATCHING
** =======================================================
*/


#define CAP_UNFINISHED	(-1)
#define CAP_POSITION	(-2)

typedef struct MatchState
{
	const char *src_init;  /* init of source string */
	const char *src_end;  /* end (`\0') of source string */
	lua_State *	L;
	int			level;  /* total number of captures (finished or unfinished) */
	struct
	{
		const char *init;
		ptrdiff_t	len;
	} capture[LUA_MAXCAPTURES];
} MatchState;


#define L_ESC		'%'
#define SPECIALS	"^$*+?.([%-"


static int 
check_capture (MatchState *ms, int l)
{
	l -= '1';
	if (l < 0 || l >= ms->level || ms->capture[l].len == CAP_UNFINISHED)
		return luaL_error(ms->L, "invalid capture index");

	return l;
}


static int 
capture_to_close (MatchState *ms) 
{
	int level = ms->level;
	for (level--; level>=0; level--)
		if (ms->capture[level].len == CAP_UNFINISHED) return level;

	return luaL_error(ms->L, "invalid pattern capture");
}


static const char *
classend (MatchState *ms, const char *p)
{
	switch (*p++)
	{
	case L_ESC: 
		{
			if (*p == '\0')
				luaL_error(ms->L, "malformed pattern (ends with " LUA_QL("%%") ")");
			return p+1;
		}
	case '[': 
		{
			if (*p == '^') p++;
			do /* look for a `]' */
			{  
				if (*p == '\0')
					luaL_error(ms->L, "malformed pattern (missing " LUA_QL("]") ")");
				if (*(p++) == L_ESC && *p != '\0')
					p++;  /* skip escapes (e.g. `%]') */
			} while (*p != ']');
			return p+1;
		}
	default:
		{
			return p;
		}
	}
}


static int 
match_class (int c, int cl)
{
	int res;
	switch (tolower(cl))
	{
	case 'a' : res = isalpha(c); break;
	case 'c' : res = iscntrl(c); break;
	case 'd' : res = isdigit(c); break;
	case 'l' : res = islower(c); break;
	case 'p' : res = ispunct(c); break;
	case 's' : res = isspace(c); break;
	case 'u' : res = isupper(c); break;
	case 'w' : res = isalnum(c); break;
	case 'x' : res = isxdigit(c); break;
	case 'z' : res = (c == 0); break;
	default: return (cl == c);
	}
	return (islower(cl) ? res : !res);
}


static int 
matchbracketclass (int c, const char *p, const char *ec) 
{
	int sig = 1;
	if (*(p+1) == '^')
	{
		sig = 0;
		p++;  /* skip the `^' */
	}
	while (++p < ec)
	{
		if (*p == L_ESC)
		{
			p++;
			if (match_class(c, uchar(*p)))
				return sig;
		}
		else if ((*(p+1) == '-') && (p+2 < ec)) 
		{
			p+=2;
			if (uchar(*(p-2)) <= c && c <= uchar(*p))
				return sig;
		}
		else if (uchar(*p) == c) return sig;
	}
	return !sig;
}


static int 
singlematch (int c, const char *p, const char *ep) 
{
	switch (*p)
	{
	case '.': return 1;  /* matches any char */
	case L_ESC: return match_class(c, uchar(*(p+1)));
	case '[': return matchbracketclass(c, p, ep-1);
	default:  return (uchar(*p) == c);
	}
}


static const char *match (MatchState *ms, const char *s, const char *p);


static const char *
matchbalance (MatchState *ms, const char *s, const char *p)
{
	if (*p == 0 || *(p+1) == 0)
		luaL_error(ms->L, "unbalanced pattern");
	if (*s != *p)
		return NULL;
	else
	{
		int b = *p;
		int e = *(p+1);
		int cont = 1;
		while (++s < ms->src_end) 
		{
			if (*s == e)
			{
				if (--cont == 0) return s+1;
			}
			else if (*s == b) cont++;
		}
	}

	return NULL;  /* string ends out of balance */
}


static const char *
max_expand (MatchState *ms, const char *s, const char *p, const char *ep) 
{
	ptrdiff_t i = 0;  /* counts maximum expand for item */
	while ((s+i)<ms->src_end && singlematch(uchar(*(s+i)), p, ep))
		i++;
	/* keeps trying to match with the maximum repetitions */
	while (i>=0)
	{
		const char *res = match(ms, (s+i), ep+1);
		if (res) return res;
		i--;  /* else didn't match; reduce 1 repetition to try again */
	}

	return NULL;
}


static const char *
min_expand (MatchState *ms, const char *s, const char *p, const char *ep) 
{
	for (;;) 
	{
		const char *res = match(ms, s, ep+1);
		if (res != NULL)
			return res;
		else if (s<ms->src_end && singlematch(uchar(*s), p, ep))
			s++;  /* try with one more repetition */
		else return NULL;
	}
}


static const char *
start_capture (MatchState *ms, const char *s, const char *p, int what) 
{
	const char *res;
	int level = ms->level;
	if (level >= LUA_MAXCAPTURES) luaL_error(ms->L, "too many captures");
	ms->capture[level].init = s;
	ms->capture[level].len = what;
	ms->level = level+1;
	if ((res=match(ms, s, p)) == NULL)  /* match failed? */
		ms->level--;  /* undo capture */

	return res;
}


static const char *
end_capture (MatchState *ms, const char *s, const char *p) 
{
	int l = capture_to_close(ms);
	const char *res;
	ms->capture[l].len = s - ms->capture[l].init;  /* close capture */
	if ((res = match(ms, s, p)) == NULL)  /* match failed? */
		ms->capture[l].len = CAP_UNFINISHED;  /* undo capture */

	return res;
}


static const char *
match_capture (MatchState *ms, const char *s, int l)
{
	size_t len;
	l = check_capture(ms, l);
	len = ms->capture[l].len;
	if ((size_t)(ms->src_end-s) >= len &&
		memcmp(ms->capture[l].init, s, len) == 0)
		return s+len;

	else return NULL;
}


static const char *
match (MatchState *ms, const char *s, const char *p) 
{
init: /* using goto's to optimize tail recursion */
	switch (*p) 
	{
	case '(': 
		{  /* start capture */
			if (*(p+1) == ')')  /* position capture? */
				return start_capture(ms, s, p+2, CAP_POSITION);
			else
				return start_capture(ms, s, p+1, CAP_UNFINISHED);
		}
	case ')': 
		{  /* end capture */
			return end_capture(ms, s, p+1);
		}
	case L_ESC:
		{
			switch (*(p+1)) 
			{
			case 'b':
				{  /* balanced string? */
					s = matchbalance(ms, s, p+2);
					if (s == NULL) return NULL;
					p+=4; goto init;  /* else return match(ms, s, p+4); */
				}
			case 'f': 
				{  /* frontier? */
					const char *ep; char previous;
					p += 2;
					if (*p != '[')
						luaL_error(ms->L, "missing " LUA_QL("[") " after "
						LUA_QL("%%f") " in pattern");
					ep = classend(ms, p);  /* points to what is next */
					previous = (s == ms->src_init) ? '\0' : *(s-1);
					if (matchbracketclass(uchar(previous), p, ep-1) ||
						!matchbracketclass(uchar(*s), p, ep-1)) return NULL;
					p=ep; goto init;  /* else return match(ms, s, ep); */
				}
			default: 
				{
					if (isdigit(uchar(*(p+1))))	/* capture results (%0-%9)? */
					{  
						s = match_capture(ms, s, uchar(*(p+1)));
						if (s == NULL) return NULL;
						p+=2; goto init;  /* else return match(ms, s, p+2) */
					}
					goto dflt;  /* case default */
			 }
			}
		}
	case '\0': 
		{  /* end of pattern */
			return s;  /* match succeeded */
		}
	case '$': 
		{
			if (*(p+1) == '\0')  /* is the `$' the last char in pattern? */
				return (s == ms->src_end) ? s : NULL;  /* check end of string */
			else goto dflt;
		}
	default: dflt:
		{  /* it is a pattern item */
			const char *ep = classend(ms, p);  /* points to what is next */
			int m = s<ms->src_end && singlematch(uchar(*s), p, ep);
			switch (*ep) 
			{
			case '?':	/* optional */
				{  
					const char *res;
					if (m && ((res=match(ms, s+1, ep+1)) != NULL))
						return res;
					p=ep+1; goto init;  /* else return match(ms, s, ep+1); */
				}
			case '*':	/* 0 or more repetitions */
				{  
					return max_expand(ms, s, p, ep);
				}
			case '+':	/* 1 or more repetitions */
				{  
					return (m ? max_expand(ms, s+1, p, ep) : NULL);
				}
			case '-': /* 0 or more repetitions (minimum) */
				{  
					return min_expand(ms, s, p, ep);
				}
			default: 
				{
					if (!m) return NULL;
					s++; p=ep; goto init;  /* else return match(ms, s+1, ep); */
			 }
			}
		}
	}
}



static const char *
lmemfind (const char *s1, size_t l1, const char *s2, size_t l2) 
{
	if (l2 == 0)
		return s1;  /* empty strings are everywhere */
	else if (l2 > l1) 
		return NULL;  /* avoids a negative `l1' */
	else 
	{
		const char *init;  /* to search for a `*s2' inside `s1' */
		l2--;  /* 1st char will be checked by `memchr' */
		l1 = l1-l2;  /* `s2' cannot be found after that */
		while (l1 > 0 && (init = (const char *)memchr(s1, *s2, l1)) != NULL) 
		{
			init++;   /* 1st char is already checked */
			if (memcmp(init, s2+1, l2) == 0)
				return init-1;
			else	/* correct `l1' and `s1' to try again */
			{  
				l1 -= init-s1;
				s1 = init;
			}
		}
		return NULL;  /* not found */
	}
}


static void 
push_onecapture (MatchState *ms, int i, const char *s, const char *e)
{
	if (i >= ms->level)
	{
		if (i == 0)  /* ms->level == 0, too */
			lua_pushlstring(ms->L, s, e - s);  /* add whole match */
		else
			luaL_error(ms->L, "invalid capture index");
	}
	else
	{
		ptrdiff_t l = ms->capture[i].len;
		if (l == CAP_UNFINISHED) luaL_error(ms->L, "unfinished capture");
		if (l == CAP_POSITION)
			lua_pushinteger(ms->L, ms->capture[i].init - ms->src_init + 1);
		else
			lua_pushlstring(ms->L, ms->capture[i].init, l);
	}
}


static int
push_captures (MatchState *ms, const char *s, const char *e)
{
	int i;
	int nlevels = (ms->level == 0 && s) ? 1 : ms->level;
	luaL_checkstack(ms->L, nlevels, "too many captures");
	for (i = 0; i < nlevels; i++)
		push_onecapture(ms, i, s, e);

	return nlevels;  /* number of strings pushed */
}


static int 
str_find_aux (lua_State *L, int find) 
{
	size_t l1, l2;
	const char *s = luaL_checklstring(L, 1, &l1);
	const char *p = luaL_checklstring(L, 2, &l2);
	ptrdiff_t init = posrelat(luaL_optinteger(L, 3, 1), l1) - 1;
	if (init < 0) init = 0;
	else if ((size_t)(init) > l1) init = (ptrdiff_t)l1;
	if (find && (lua_toboolean(L, 4) ||  /* explicit request? */
		strpbrk(p, SPECIALS) == NULL))
	{  /* or no special characters? */
		/* do a plain search */
		const char *s2 = lmemfind(s+init, l1-init, p, l2);
		if (s2) 
		{
			lua_pushinteger(L, s2-s+1);
			lua_pushinteger(L, s2-s+l2);
			return 2;
		}
	}
	else
	{
		MatchState ms;
		int anchor = (*p == '^') ? (p++, 1) : 0;
		const char *s1=s+init;
		ms.L = L;
		ms.src_init = s;
		ms.src_end = s+l1;
		do 
		{
			const char *res;
			ms.level = 0;
			if ((res=match(&ms, s1, p)) != NULL) 
			{
				if (find) 
				{
					lua_pushinteger(L, s1-s+1);  /* start */
					lua_pushinteger(L, res-s);   /* end */
					return push_captures(&ms, NULL, 0) + 2;
				}
				else
					return push_captures(&ms, s1, res);
			}
		} while (s1++ < ms.src_end && !anchor);
	}
	lua_pushnil(L);  /* not found */

	return 1;
}


static int 
str_find (lua_State *L)
{
	return str_find_aux(L, 1);
}


static int
str_match (lua_State *L)
{
	return str_find_aux(L, 0);
}


static int
gmatch_aux (lua_State *L) 
{
	MatchState ms;
	size_t ls;
	const char *s = lua_tolstring(L, lua_upvalueindex(1), &ls);
	const char *p = lua_tostring(L, lua_upvalueindex(2));
	const char *src;
	ms.L = L;
	ms.src_init = s;
	ms.src_end = s+ls;
	for (src = s + (size_t)lua_tointeger(L, lua_upvalueindex(3));
		src <= ms.src_end;
		src++) 
	{
		const char *e;
		ms.level = 0;
		if ((e = match(&ms, src, p)) != NULL)
		{
			lua_Integer newstart = e-s;
			if (e == src) newstart++;  /* empty match? go at least one position */
			lua_pushinteger(L, newstart);
			lua_replace(L, lua_upvalueindex(3));
			return push_captures(&ms, src, e);
		}
	}

	return 0;  /* not found */
}


static int 
gmatch (lua_State *L)
{
	luaL_checkstring(L, 1);
	luaL_checkstring(L, 2);
	lua_settop(L, 2);
	lua_pushinteger(L, 0);
	lua_pushcclosure(L, gmatch_aux, 3);

	return 1;
}


static int 
gfind_nodef (lua_State *L) 
{
	return luaL_error(L, LUA_QL("string.gfind") " was renamed to " LUA_QL("string.gmatch"));
}


static void
add_s (MatchState *ms, luaL_Buffer *b, const char *s, const char *e) 
{
	size_t l, i;
	const char *news = lua_tolstring(ms->L, 3, &l);
	for (i = 0; i < l; i++) 
	{
		if (news[i] != L_ESC)
			luaL_addchar(b, news[i]);
		else 
		{
			i++;  /* skip ESC */
			if (!isdigit(uchar(news[i])))
				luaL_addchar(b, news[i]);
			else if (news[i] == '0')
				luaL_addlstring(b, s, e - s);
			else
			{
				push_onecapture(ms, news[i] - '1', s, e);
				luaL_addvalue(b);  /* add capture to accumulated result */
			}
		}
	}
}


static void
add_value (MatchState *ms, luaL_Buffer *b, const char *s, const char *e) 
{
	lua_State *L = ms->L;
	switch (lua_type(L, 3)) 
	{
	case LUA_TNUMBER:
	case LUA_TSTRING:
		{
			add_s(ms, b, s, e);
			return;
		}
	case LUA_TFUNCTION:
		{
			int n;
			lua_pushvalue(L, 3);
			n = push_captures(ms, s, e);
			lua_call(L, n, 1);
			break;
		}
	case LUA_TTABLE:
		{
			push_onecapture(ms, 0, s, e);
			lua_gettable(L, 3);
			break;
		}
	default:
		{
			luaL_argerror(L, 3, "string/function/table expected"); 
			return;
		}
	}
	if (!lua_toboolean(L, -1))	 /* nil or false? */
	{ 
		lua_pop(L, 1);
		lua_pushlstring(L, s, e - s);  /* keep original text */
	}
	else if (!lua_isstring(L, -1))
		luaL_error(L, "invalid replacement value (a %s)", luaL_typename(L, -1)); 
	luaL_addvalue(b);  /* add result to accumulator */
}


static int 
str_gsub (lua_State *L)
{
	size_t srcl;
	const char *src = luaL_checklstring(L, 1, &srcl);
	const char *p = luaL_checkstring(L, 2);
	int max_s = luaL_optint(L, 4, srcl+1);
	int anchor = (*p == '^') ? (p++, 1) : 0;
	int n = 0;
	MatchState ms;
	luaL_Buffer b;
	luaL_buffinit(L, &b);
	ms.L = L;
	ms.src_init = src;
	ms.src_end = src+srcl;
	while (n < max_s)
	{
		const char *e;
		ms.level = 0;
		e = match(&ms, src, p);
		if (e) 
		{
			n++;
			add_value(&ms, &b, src, e);
		}
		if (e && e>src) /* non empty match? */
			src = e;  /* skip it */
		else if (src < ms.src_end)
			luaL_addchar(&b, *src++);
		else break;
		if (anchor) break;
	}
	luaL_addlstring(&b, src, ms.src_end-src);
	luaL_pushresult(&b);
	lua_pushinteger(L, n);  /* number of substitutions */

	return 2;
}

/* }====================================================== */


/* maximum size of each formatted item (> len(format('%99.99f', -1e308))) */
#define MAX_ITEM	512
/* valid flags in a format specification */
#define FLAGS	"-+ #0"
/*
** maximum size of each format specification (such as '%-099.99d')
** (+10 accounts for %99.99x plus margin of error)
*/
#define MAX_FORMAT	(sizeof(FLAGS) + sizeof(LUA_INTFRMLEN) + 10)


static void
addquoted (lua_State *L, luaL_Buffer *b, int arg)
{
	size_t l;
	const char *s = luaL_checklstring(L, arg, &l);
	luaL_addchar(b, '"');
	while (l--) 
	{
		switch (*s) {
	  case '"': case '\\': case '\n': 
		  {
			  luaL_addchar(b, '\\');
			  luaL_addchar(b, *s);
			  break;
		  }
	  case '\0': 
		  {
			  luaL_addlstring(b, "\\000", 4);
			  break;
		  }
	  default: 
		  {
			  luaL_addchar(b, *s);
			  break;
		  }
		}
		s++;
	}
	luaL_addchar(b, '"');
}

static const char *
scanformat (lua_State *L, const char *strfrmt, char *form)
{
	const char *p = strfrmt;
	while (strchr(FLAGS, *p)) p++;  /* skip flags */
	if ((size_t)(p - strfrmt) >= sizeof(FLAGS))
		luaL_error(L, "invalid format (repeated flags)");
	if (isdigit(uchar(*p))) p++;  /* skip width */
	if (isdigit(uchar(*p))) p++;  /* (2 digits at most) */
	if (*p == '.')
	{
		p++;
		if (isdigit(uchar(*p))) p++;  /* skip precision */
		if (isdigit(uchar(*p))) p++;  /* (2 digits at most) */
	}
	if (isdigit(uchar(*p)))
		luaL_error(L, "invalid format (width or precision too long)");
	*(form++) = '%';
	strncpy(form, strfrmt, p - strfrmt + 1);
	form += p - strfrmt + 1;
	*form = '\0';

	return p;
}


static void 
addintlen (char *form) 
{
	size_t l = strlen(form);
	char spec = form[l - 1];
	strcpy(form + l - 1, LUA_INTFRMLEN);
	form[l + sizeof(LUA_INTFRMLEN) - 2] = spec;
	form[l + sizeof(LUA_INTFRMLEN) - 1] = '\0';
}


static int 
str_format (lua_State *L) 
{
	int arg = 1;
	size_t sfl;
	const char *strfrmt = luaL_checklstring(L, arg, &sfl);
	const char *strfrmt_end = strfrmt+sfl;
	luaL_Buffer b;
	luaL_buffinit(L, &b);
	while (strfrmt < strfrmt_end) 
	{
		if (*strfrmt != L_ESC)
			luaL_addchar(&b, *strfrmt++);
		else if (*++strfrmt == L_ESC)
			luaL_addchar(&b, *strfrmt++);  /* %% */
		else /* format item */
		{ 
			char form[MAX_FORMAT];  /* to store the format (`%...') */
			char buff[MAX_ITEM];  /* to store the formatted item */
			arg++;
			strfrmt = scanformat(L, strfrmt, form);
			switch (*strfrmt++) 
			{
			case 'c': 
				{
					sprintf(buff, form, (int)luaL_checknumber(L, arg));
					break;
				}
			case 'd':  case 'i': 
				{
					addintlen(form);
					sprintf(buff, form, (LUA_INTFRM_T)luaL_checknumber(L, arg));
					break;
				}
			case 'o':  case 'u':  case 'x':  case 'X': 
				{
					addintlen(form);
					sprintf(buff, form, (unsigned LUA_INTFRM_T)luaL_checknumber(L, arg));
					break;
				}
			case 'e':  case 'E': case 'f':
			case 'g': case 'G': 
				{
					sprintf(buff, form, (double)luaL_checknumber(L, arg));
					break;
				}
			case 'q': 
				{
					addquoted(L, &b, arg);
					continue;  /* skip the 'addsize' at the end */
				}
			case 's': 
				{
					size_t l;
					const char *s = luaL_checklstring(L, arg, &l);
					if (!strchr(form, '.') && l >= 100) {
						/* no precision and string is too long to be formatted;
						keep original string */
						lua_pushvalue(L, arg);
						luaL_addvalue(&b);
						continue;  /* skip the `addsize' at the end */
					}
					else 
					{
						sprintf(buff, form, s);
						break;
					}
				}
			default: 
				{  /* also treat cases `pnLlh' */
					return luaL_error(L, "invalid option to " LUA_QL("format"));
				}
			}
			luaL_addlstring(&b, buff, strlen(buff));
		}
	}
	luaL_pushresult(&b);

	return 1;
}


static const luaL_Reg strlib[] = 
{
	{"byte",	str_byte},
	{"char",	str_char},
	{"dump",	str_dump},
	{"find",	str_find},
	{"format",	str_format},
	{"gfind",	gfind_nodef},
	{"gmatch",	gmatch},
	{"gsub",	str_gsub},
	{"len",		str_len},
	{"lower",	str_lower},
	{"match",	str_match},
	{"rep",		str_rep},
	{"reverse", str_reverse},
	{"sub",		str_sub},
	{"upper",	str_upper},
	{NULL,		NULL}
};


static void 
createmetatable (lua_State *L) 
{
	lua_createtable(L, 0, 1);  /* create metatable for strings */
	lua_pushliteral(L, "");  /* dummy string */
	lua_pushvalue(L, -2);
	lua_setmetatable(L, -2);  /* set string metatable */
	lua_pop(L, 1);  /* pop dummy string */
	lua_pushvalue(L, -2);  /* string library... */
	lua_setfield(L, -2, "__index");  /* ...is the __index metamethod */
	lua_pop(L, 1);  /* pop metatable */
}


/*
** Open string library
*/
LUALIB_API int 
luaopen_string (lua_State *L)
{
	luaL_register(L, LUA_STRLIBNAME, strlib);
#if defined(LUA_COMPAT_GFIND)
	lua_getfield(L, -1, "gmatch");
	lua_setfield(L, -2, "gfind");
#endif
	createmetatable(L);

	return 1;
}

